Needling monofilament sutures

ABSTRACT

The breakage of monofilament stainless steel sutures and other monofilament sutures at the point of attachment to eyeless needles is markedly reduced by counterboring the eyeless needle so that flexing is reduced at the point of crimp and the sharp radius of curvature at the departure from the needle is minimized.

United States Patent [1 1 Messer et a1.

[ 1 Oct. 7, 1975 15 NEEDLING MONOFILAMENT SUTURES [75] Inventors: Philip Joseph Messer, Brookfield;

S01 Singerman, E. Norwalk, both of Conn.

[73] Assignee: American Cyanamid Company,

Stamford, Conn.

[22] Filed: May 22, 1974 [21] Appl. No.: 472,264

[52] US. Cl. 128/339; 223/102 [51] Int. C1. A6lB 17/06 [58] Field of Search 128/3355, 339; 223/102;

[56] References Cited UNITED STATES PATENTS Baule 128/339 2,583,625 1/1952 Bergan 29/517 2,728,343 12/1955 Everett 128/339 3,160,157 12/1964 Chisman.... 128/339 3,265,070 8/1966 Kurtz 128/339 3,394,704 7/1968 Dery 128/339 FOREIGN PATENTS OR APPLICATIONS 455,640 5/1913 France 128/339 Primary Examiner-Dalton L. Truluck Attorney, Agent, or FirmSamue| Branch Walker [57] ABSTRACT The breakage of monofilament stainless steel sutures and other monofilament sutures at the point of attachment to eyeless needles is markedly reduced by counterboring the eyeless needle so that flexing is reduced at the point of crimp and the sharp radius of curvature at the departure from the needle is minimized.

1 Claim, 9 Drawing Figures U. S. Patent Oct. 7,1975 Sheet 1 of 2 3,910,282

a I //2' i NEEDLING MONOFILAMENT SUTURES BACKGROUND OF THE INVENTION Single use, eyeless, ordrilled end needles are meeting with increasing acceptance for surgical suture usages. These are needles in which a concentric axial hole is formed in the base of the needle into which the end of a suture is placed and crimped. An eyed needle requires that the suture be passed through the eye and folded so that there is a double thickness of suture in the eye of the needle which tends to cause tissue damage as the doubled portion of the suture is pulled through the tissue. This is particularly damaging with monofilament sutures which are stiffer than polyfilamentary sutures. Flanged needles in which the end of the needle is swaged into an open U-shaped trough which is crimped about the suture are apt to have a discontinuity or tissue-tearing unevenness at the start of the flange and additionally present problems in hardening. It is desirable to harden the needle before the flange is bent around the suture and such hardening tends to render the flange brittle.

One of the problems in using a drilled end needle on a suture is that during use the suture may be bent sharply at the point of attachment to the needle where the suture comes out of the hole in the end of the needle, which may cause the suture to break. These problems have been recognized and various expedients for solving the problems have been devised but new and improved systems are in demand.

DESCRIPTION OF PRIOR ART US. Pat. No. 1,558,037, Morton, SURGICAL NEE- DLE AND SUTURE ASSEMBLY AND METHOD OF MAKING THE SAME, Oct. 20, I925, shows a drilled end needle crimped on a suture.

US. Pat. No. 2,910,983, Everett, SEWING NEE- DLES, Nov. 3, 1959. shows a drilled end needle, in which exterior convolutions are formed in the needle at the butt end, and which convolutions are crimped into the suture. A flared entrance to the needle socket is provided.

US. Pat. No. 3,038,475, Orcutt, SURGICAL NEE-.

DLES AND MANUFACTURE OF SAME, June 12, 1962, shows curved and straight drilled end needles with hollow ground points.

US Pat. No. 3,125,095, Kaufman et al, FLEXIBLE STAINLESS STEEL SUTURES, Mar. 17, 1964, shows a polyfilamentary stainless steel suture, crimped in a drilled end needle.

US. Pat. No. 3,31 L1 10, Singerman et al, FLEXIBLE COMPOSITE SUTURE HAVING A TANDEM LINK- AGE, Mar. 28, 1967, shows a flexible monofilament leader between an eyeless surgical needle and a monofilament stainless steel suture. Column 3 of this patent describes tests of flexibility at the needlesuture junction.

US. application, Ser. No. 343,753, A. S. Taylor and H. M. Weinert. LASER MANUFACTURE OF SU- TURE NEEDLES, Mar. 22, I973, shows using a laser beam to form a hole in the end of a neelde blank, which hole is tapered by the nature of the laser drilling. The hole is then swaged to size and cylindrical shape.

SUMMARY OF THE INVENTION It has now been found that the flex life of monofilament sutures. particularly stainless steel sutures, may

be increased by counterboring the suture socket in the drilled end of the needle and rounding the edges which contact the suture. Conveniently, a slight countersink or chamfcr is formed at the entrance to the suture socket and at the transition from the counterbore to suture-holding bore.

Whereas in the past it has been customary to use a crimp which is frequently substantially all the way around the drilled end of the needle, to reduce the size of the suture-holding socket and crimp it against the suture, it has now been found that excellent holding characteristics are achieved by using a nose die which presses in only a small part of the circumference and presses that part of the circumference into the sutureholding socket to press the suture against the opposing wall of the suture-holding socket. Much larger nose crimps are quite conventional in the electrical industries to crimp connectors onto the ends of wires. A miniaturized crimp of the same typ e is used with the suture needles, because of the'smaller sizes of the products.

Particularly, with curved needles such as a or /2 circle needle, the needle may twist or roll in the suture needle holder. The present needles may have flats, or ridges, or grooves formed in the surface of the needle, preferably at about right angles to the plane of curvature of the needle so that serrations on the suture needle holder will interlock with such flats or serrations or grooves and give better control to the surgeon in his use of the surgical needle.

Other advantages and objects of the present invention are apparent from the following detailed description and drawings. 1

DRAWINGS FIG. 1 shows a curved surgical needle to which is attached a stainless steel suture.

FIG. 2 is an enlarged view in partial cross-section showing a nose die crimping counterbored surgical needle to a stainless steel monofilament wire.

FIG. 3 is an end view of a counterbored needle showing a stainless a steel suture wire therein.

FIG. 4 is a section along cutting plane 44 of FIG. 1 showing the needle crimped to a suture.

FIG. 5 is an enlarged view of a counterbore in the end of a surgical needle.

FIG. 6 is the same section of the same needle as FIG. 5 after the needle has been crimped to a monofilament suture.

FIG. 7 is the section along cutting plane AA of FIG. 1 showing a modification having flats on a needle to cooperate with needle holding forceps.

FIG. 8 is the section along cutting plane AA of FIG. 1 showing a modification having ridges on a surgical needle to cooperate with needle holding forceps.

FIG. 9 is a section along plane AA of FIG. 1 showing a modification having grooves in a surgical needle to cooperate with needle holding forceps.

As shown in FIG. 1, a surgical suture 11 is attached to an eyeless suture needle 12. Conveniently, but not necessarily, the surgical suture is a monofilament stainless steel wire. In nearly all countries, the sizes of sutures are to conform to a governmental or industrial standard. In the United States the sizes are to conform to the United States Pharmacopoeia standards. Be

cause each of the several sizes has a maximum diameter and because the greater diameter of the suture, the stronger. it is customary to merchandise sutures which are just under the maximum diameter and, hence. have the greatest strength for each standard size.

Whereas, the present counterbored eyeless suture needle has its greatest advantages in connection with a monofilament wire suture, the needle may be used with monofilamcnts of plastics such as polyesters, polyethylene, polypropylene, or polyglycolic acid. The biggest advantages are in connection with wire which tends to work harden and fracture when bent at the junction of the suture and needle.

The suture may be any convenient length and may have a needle on each end, as is frequently used in operating room procedures. The needle and suture are here further described in connection with a single armed suture, that is, one having but one needle on one end thereof, and in connection with a stainless steel suture, as other adaptations are similar.

The needle itself 12 is shown as curved. Any of the conventional forms of surgical needles may be used, including straight, curved, triangular, duck billed, reversed cutting, or other configuration of cutting point and curvature which meets the preferences of a surgeon for a particular operation technique.

As shown in FIG. 5, the needles are usually made from a round wire with the suture holding bore 13 coaxial and concentric with the back end of the needle 14, A counter-bore 15 extends into the back end of the needle. Whereas the suture holding bore and the concentric counterbore may be formed by the use of lasers, electrolytic etching, or other metal working technique, the currently used process is drilling using small size metal working drills. It is quite convenient and trade practice to use terminology in describing the parts of the needle as if it were formed by drilling even though the actual metal working technique may have been different.

It is the configuration and not the method of obtaining the configuration which is important.

The front end of the suture holding bore is a flat cone 16 as is conventionally formed by the fluted lips on a metal drill.

A similar flat conical end on the drill which forms the counterbore 15 leaves a conical or chamfered section 17 between the counterbore 15 and the suture holding bore 13. This chamfer is normally formed by the front lips on the drill forming the counterbore, and has the additional advantage of funneling the end of the suture 11 into the suture holding bore 13 during assembly. At the back end of the needle 14 and concentric with the back end of a counterbore is a countersink section 18 which is a chamfer leading into the counterbore.

In forming the needle, either the counterbore 15 or the suture holding bore 13 may be drilled first, depending upon the equipment available and the chamfered section 17 and the flat cone 16 are normally inherently formed by the metal working tools. The countersunk section 18 may be formed by the lips of a larger drill or a small size centering drill.

Depending upon the manufacturing techniques used, the back end of the needle may be cut off square, or may be turned square on a drilling machine or lathe, slightly countersunk and the counterbore and suture holding bores formed. It is frequently convenient to spot the end of a needle, touch it with a countersink, and then drill the counterbore. The counterbore being the larger of the bores and shallower, it is easier to form the larger hole, which then requires the suture holding bore 13 be drilled to a shallower depth, as it starts part way into needle, and the problems of deep drilling with a very small drill are minimized.

Conveniently, the edges, particularly at the back end of the needle, are slightly rounded during formation or by tumbling or sandblasting during the polishing of the needle.

Needle point 19 at the front end of the needle is formed and sharpened by conventional techniques into a desired shape.

Conveniently, but not necessarily, the shank 20 of the needle between the point and the drilled end has a portion of its length of non-round shank to prevent slipping in engagement with needle holding forceps.

As shown in FIG. 7, a flat portion on the inside and the outside of the radius of curvature or in any other location, gives needle flats 21 which can be grasped with the needle holding forceps to secure the needle in said forceps against any tendency to roll.

Similar protection against rolling may be provided by ridges 22 formed on the round portion of the needle by swaging during manufacture, as shown in FIG. 8.

The modification of FIG. 9 shows grooves 23 formed into the needle to provide gripping action and keep the needle from slipping in the needle holding forceps.

The ridges, grooves or flats may be formed by swaging, cold drawing, etching, grinding, or other conventional metal working techniques.

The method of attaching the suture 11 to the eyeless suture needle 12 is shown in FIG. 2. The end of the surgical suture is small enough to fit into the suture holding bore and it is inserted until it bottoms against the bottom of the suture holding bore and while being held in this position is crimped to hold the suture. As shown in FIG. 2, a die 24 having slightly rounded corners is forced against the side of the needle to displace part of the metal of the needle into the suture holding bore to crimp and hold the suture in the bore. The crimp 25, as shown in FIG. 4, displaces metal into the suture holding bore and frictionally engages the suture.

The use of such nose dies to crimp a sleeve against a wire are well known in the electrical industry where crimping tools form a viable alternative to soldering in assembly. A properly crimped connector at the end of an electrical connector has long been recognized as an economical and long lived manufacturing technique.

In sutures, the size of the nose and the entire assembly is comparatively small, and requires small dies and holding anvils proportioned to the size of the suture and needle being assembled.

As shown in FIG. 2, the suture extends from the back end of the needle and is held against one side of the suture holding bore by the swaging effect of the crimp. As

shownin FIG. 2, the counterbore then prevents a sharp bend in the suture 11 as it emerges from the suture holding bore 13. This protects the suture where it is deformed by crimping from bending action and permits only a comparatively slight bending in the suture inside of the counterbore.

Any substantial bending must occur as a suture emerges from the counterbore and is essentially free from working stresses resulting from crimping the suture to the needle. The counterbore also increases the radius of curvature of the suture at the back end of a needle and aids in reducing the likelihood of fatigue failure at the point of attachment.

Whereas the relative proportions may vary somewhat with the materials of construction and the availability and capabilities of the metal working tools used to form the suture hole and counterbore, a convenient and effective relationship between the nominal suture size, the actual suture diameter, the needle diameter, the suture hole diameter and depth, and the counterbore diameter and depth is shown by the following Table 1.

A nose on a die which gives an imprint about 0.015 inch wide and about 0.025 inch longitudinally of the needle and deep enough to retain the suture in the suture hold is effective. The adequacy of the crimp is best determined by testing. If the crimp is too shallow, the suture pulls out. If it is too deep, it can squeeze off the end of the suture. By maintaining the depth of the crimped nose between these limits, effective and rapid assembly may be obtained.

As is obvious to one skilled in the art, a suitable anvil such as a block of sttel having a groove therein adapted to hold the back half of the needle is used as the backing against which the die presses the needle during crimping.

Where a concentric set of dies is available, it is feasible to crimp the needle arround the suture for 180 or 360 or whatever are the design parameters of conventional needle attaching equipment.

The advantages of the present counterbored needle as compared with a conventional drilled end needle is shown by results obtained on using a Tinius Olsen M1T TABLE II Monostrand Stainless Steel Wire Size Flexes to Break Wire 3/0 4/0 5/0 (150 g. (150 g. (100 g. tension) tension) tension) Conventional Crimp l 9 l l (ounterhored Needle Single Nose Die 39 43 42 As cana be seen. a 3 to times increase in flexing to failure is obtained by using the present counterbored needle assembly.

Whereas in use a surgeon is primarily concerned with the suture breaking under the l or 2 flexes which may occur during insertion of the needle, the above table is very meaningful as a measure of the increased flex resistance which permits the surgeon to use a monofilament steel suture with marked reduction in the likelihood of a failure at the point of attachment of the suture to a needle.

Wire sutures are extremely useful in certain surgical procedures particularly with bone, cartilage, or other tissues in which a minimal of extensibility is desired. The additional resistance to failure at the attachment of the needle permits the wire to be emplaced at a desired location with greater ease and certainty.

Whereas the above table gives representative proportions, it is to be noted that the counterbore should have a depth of at least about /2 its diameter and preferably nearly that of its diameter and the counterbore should have a diameter of about 1 /2 to 2 times the diameter of the suture hole and that the suture hole itself should have a depth of about 4 to 5 times its diameter, deeper counterbores and deeper suture attaching bores may be used where the capabilities of the metal working machines used in the manufacture of the needles permit such greater depth. The cost and difficulty of drilling small deep holes normally cause the suture holding bores to be drilled to as shallow a depth as is consistent with adequate strength development, in the attachment of the needle to the suture.

We claim:

1. A stainless steel suture in combination with a surgical suture needle comprising: a stainless steel monofilament surgical suture and a needle, the needle comprising a pointed end on said needle, a round cylindrical shank portion of said needle, and an axial suture socket portion at the back end of the needle and of uniform diameter with the shank, said socket portion consisting, before crimping, ofa suture holding bore slightly larger than said suture at the inner end of the socket, and an essentially concentric cylindrical counterbore slightly larger than the suture holding bore, between said suture holding bore and the back end of the needle, said suture being inserted and retained in said suture holding bore in said needle, retention being by at least a portion of said suture holding bore being crimped into frictionally engaging relationship with said suture, in which the stainless steel suture diameter, the suture holding bore diameter and depth, the counterbore diameter and depth, and needle diameter are selected from the table:

and the crimp shows an imprint about 0.015 inch wide, about 0.025 inch longitudinally of the needle, and deep enough to firmly hold the suture, whereby said counter- 5 bore prevents bending of said suture adjacent to the crimped portion, and insures that flexing of the suture occurs behind the suture holding bore. 

1. A stainless steel suture in combination with a surgical suture needle comprising: a stainless steel monofilament surgical suture and a needle, the needle comprising a pointed end on said needle, a round cylindrical shank portion of said needle, and an axial suture socket portion at the back end of the needle and of uniform diameter with the shank, said socket portion consisting, before crimping, of a suture holding bore slightly larger than said suture at the inner end of the socket, and an essentially concentric cylindrical counterbore slightly larger than the suture holding bore, between said suture holding bore and the back end of the needle, said suture being inserted and retained in said suture holding bore in said needle, retention being by at least a portion of said suture holding bore being crimped into frictionally engaging relAtionship with said suture, in which the stainless steel suture diameter, the suture holding bore diameter and depth, the counterbore diameter and depth, and needle diameter are selected from the table: 